HEJtEDITY AND EV@L

OW DO MENDEL'S EXPERIMENTS SHOW ~ - - ~-\ITS MAY BE_ iINANT OR RECESSIVE?_ Iendel used pea plants with contrasting traits fo == _ iments. For eg: tall/dwarf

rs, white/violet flowers, round/wrinkled seeds.crossed a tall plant with a short plant and obser K -"7-- - ight of the offspring plantse following generation.e first generation or Fl generation all the plants ze ~-ed were tall.

self-pollination of these FI generation plants he - - ed both tall plants and dwarf• in the ratio of 3: 1which he called as F2 generzf

r , indicated that Fl plants had both the factors, a ~.: - - ..'- ness and one for shortnessnly tallness trait was expressed. So he conclud .: - :::.'"factor for tallness is

_ ....•.; ant and the factor for dwarfness which was no: -.. ssed in Fl generation isssive. In other words the trait of tallness is-do =-- - - _ver the trait of shortness.

::;OW DO MENDELS EXPERIMENTS SEO y - -::.-- .-: :RAITS ARE. IN l1ERiTEDEPENDENTLY? " '

_ Iendel performed dihybrid crosses where he has - two characteristics into .sideration. For eg: Seed shape (round/wrinkled) - seed colour (green/yellow).en he crossed pea plants bearing round and greer. :~;- with pea plants bearing

- ded and yellow seeds he obtained all plants - ~ _ and yellow seeds in• generation, showing that round shape and yello - _ of the seed are dominant

~.~ en he self fertilized these Fl generation plants, --~ Ziled some plants with round ..: &CC::-i seedsand ::::;1mE>-phr:.1t:: with wrinkled a....r-=--. --::0: seeds like theirparents ill F2ieration.

ver 'there were other plants, some of which :;:0- ...::d and yellow seeds <U1d othersfyvrinkled and green seeds. This showed that r; _ss can be inherited ei ther with

reen or yellow (:01-' r. Similarly wrinkled seed _-:..... -.~ so be i:ll~e~'i~edeither \,vittUeeu or yellow trail - J'k#;e~indepcnde:- _.__ance of traits. J~,/ ~___-MAN WITH B GROUP A 1fJARR1E:: _- YlAN WITH BLOOD GROUP

••. _ND THEIR DAUGHTER HAS BLOOD G . IS THIS INFORMATION-, . .

-OUGH TO TELL YOU WHICH OF TI-IE TR...-__ - BLOOD GROUPA OR.O -IS:JMINATNT? WHY OR WHY NOT?

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'" ';',jV\\J\ .•••--The factors for different blood groups in h -gs are as follows I. 1 x: L 1- A for A; blood group, ill for B blood group and = - : :- 0 blood group.-' :.-! •.. " .

_ The genotypes for the four. different blood . _ zre as follows:' . / ~ '.-A i.A or iA iO - A group,iB iB or iBiO - B, iA -.-ill and iO iO for 0 it·oup.

'e can see that when iA iB is the genotype bo 1- .r: .:: B antigens are expf~se~.:., So ~ither A nor B nor 0 where it means no antigezr _:ood are dominant. ~ f ' i

-e, HOW IS THE SEX OF A CHILD DETE

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••.•..-;,....,.wLLl.an beings all the cells have 22 pairs of auto- ~ one pair of sexsomes or allosomes. In females the two allosor.es _~ similar and are called Xsocies.,J:J;encefemales produce only one type \J=.:. - etes, all ofthem having 22

somes and XemomosDme. -:;-,,~one allosome is n;rt-nal sized and is called ==_ :nosome and the other one-::er which is called as Y ~htQ+D-osome,Therefore - - produce two types of:5, half of them having 22 autosomes and X an - ---- _-.....er half having 22 autosomes~- hromosome.~ a male gamete With X chromosome meets the: -" gamete, the combination will

_~ and the child will be a girl. When a male gam -= ~::....Y chromosome meets the7:ete, the combination will be XY and the - .: be a boy;

T ARE-THE DIFFERENT WAYS IN WHIL- _0IVIDUALS WITH A:I1CULAR TRAIT MA YINCREASE IN POPL-=-- :---ON? -

___ a selection - Natural selection of individ ~- -:ili. adaptations to survive~ in a given en-•.•.ironment w-ill result in an increase i : ese individuals and their traits=- pulation. For eg: beetles with green colour 'V\ - _ -. ive better in forest than red

::'es which will be easily spotted by their predators .ienetic drift - When accidents occur in small pop the individuals with one.cular trait might be eliminated and the individ -- -::=: a different trait might-:-·e.In this way the trait of the surviving indivi - - -::::J.C.yincrease in the population

~ it might not give any survival advantage.rene flow - An organism migrating from its origi ~ ation to a new habitat will addwn genes to the host population. And gradually - --= vill be an increase in the, er ofoffspring with these newly added genes,

_-'le above t>NO ways involve genetic changes --=--'-;iduals with a particular trait increase in a pop .: .':':':'abilityof natural resources also change the p~_- result in an increase in individuals with a pan;

~ is another way in which=-, Increased or decreased

aits of individuals. This might- :.:-aitin a population.

---:HY i-\RE TRAITS ACQUIRED DURING 'L- - - FE-TIME OF ANINDIVID~LT INHERlTED? '~hechanges that are acquired during the life-era - ccur at cellular level and notatmosomallevel or genetic level. Especially t.t:=:- =-- not change the DNA of the germ

. (gametes) andtherefore cannot be inherited' __ offspring or the progeny.

WHY ARE THE SMALL NUMBERS OF SC?-~ G TIGERS A CAUSE OF-ORJ\Y FROM THE POINT OF VIEW OF G-=--.- csv

Tiger is an important predator in the ecosyste _ ""yson a variety of animals ...,....ose animals with adaptations to escape the tig -'- are naturally selected to survive

er and increase in numbers. In other words '- exert the natural selection which. cts evolution. The small number of tigers -,- _ ce this natural selection and

tinuation of variations in the prey animals. _ - _ -'" animals with genetic variationsight disappear without their further propaga icz; .; ence evolution might not ocelli,

--\'..ffiAT FACTORS COULD LEAD TO TIE =- - OF A NEW SPECIES?

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'- graphic isolation and reproductive isolation of o~.:. :'W1S along with accumulationzriationsdue to genetic drift or gene migration or - -' selection leads to the rise of

/ "..-speCIes. .tample in two populations of geographically isol~--=-~::eetles, let us sayan accident

iaa ed green beetles (genetic drift) and resulted in c-~~ease in red beetles in one'""i-'~?.u'on. And in the other the. green beetles surviv -== 2TOWS whereas red beetles are

*=-~ted (natural selection). Further because of some == .;variation like an increase in'=''.:illberof chromosomes the green females mate \~ cnly green males but not red.~ result a new species of beetles will be generated.

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""ILLGEOG~HICAL ISOLATION BE AM£":=' FACTOR IN THE.cCIATION OF A SELF-POLLINATINGPLAl'll ~:::CIES? WHY OR WHY NOT?

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_·0.Because the ~rit ~~p_~~~_~~!ijtlKJQ.r~pr29,L·:=:::'::geographic isolation will not-: this process in these plants. . .... .. '.' -- - .

~.1LLGEOGRAPHIC lS0LATION BE A MAle: ?_-\CTOR TNTH SPECIA TJON_~ ORGANIS.M THAT REPRODUCES ASEX· .-:"':"Y? WHY OR WElY NUl'?

• ·0.Because the single organism is involved in --l~.F!9Qll(JiW1.ans;!.itgepe.l1~1~UlJl,:-for repr.2.sl:g~!!m1.If two different organisms or=-- - .. eat populations are involved, the.::e c;{o~eto recognize the other for mating resnrs ~ -l1e>development of new species

eciation.

- _GIVE AN EXAMPLE OF CHARACTERISITC= -=::::NGUSED TO DETERNIINECLOSE T\VO SPECIES ARE IN EVOLUTIr"_ -.-3Y TERMS.

-truc{l~e of fOT~linibsin a frog, lizard, bird and -.: .3 is similar with similar bon~s .. omthis it can be assumed that they may have a c -- ancestordown the line of·-'utian.plants angiosperms and gymnosperms produce ~:..: ':Jhanerogams) while the

_ ridcphytes do not produce se~ds. So the angio .;:- - are closer to gymnosperms than;;uido phytes.

-' can elephants and Asian elephan.s arc two cl '_ _ .elated species as they belong 'tosame kingdom Animalia as both ate euxaryo - :=::=on-photosynthetic. Both ofthen:ongto the same phylum chordata as they have == -:"'ordall through their life. Theylong to the class mammalia as they have mamma _ ~:ands and family Elepliantidae 8S

- have trunks developed from their incisor teez; __ these characters showthat theyclosely related to each other then they are to ~ similar looking animals like

mammoths which have tusks developed from car - ,=- teeth.

::. CAN THE WING OF A BUTTERFL Y AND - ~ -G OF.A BAT Celli BEON"SIDERED HOMOLOGOUS ORGAI"fS? y-=-- R WHY NOT?

__ No. The wing of a butterfly is a fold of memi _- = associated with few muscles and./ -~..- '-- .•.-.~---- --,.- ..•.•.._ .•.......- ,. ; ..~..-.,..~.~,.---.. , : ,.-" ~,-".-~,.

me wing of a bat ~;efolds.of skin betwe~.g~~I.2ng:__- =--.g~rsCtn.(?llpPQrt:~~):Jy~t~1~!9.~1._"U they are notnomologous"orgalis'blitc8n be .: :: zs analogous organs as they are- ilar in furfrtion'butnoTSimifmT~; structure. - -- ..,-~.", -.. < •• ,.".,<»<~..«- ~'

---' -_., •.._;""/ •••••••••....• ,." .• ·<"'<· •._ ••.·.-"n·.."~·." ....<·,·,·'"'." ••·, .. ·,· ...•w."'••••, ••.•., ••• ~= 1\...1/

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_n.lIA1t ARE FOSSILS? HOW ARE THEY FORl ~, WHAT DO THEY TELLABOUT THE PROCESS OF EVOLUTION?

E ssils are preserved traces of earlier-organisms thz zre ~resently dead.::c organisms die, their bodies will be decomposed ~~ Iost. But once in a while, the~; or at least some parts may not decompose because -: - e enviromnent they are leftfer eg: hot mud, amber and form fossils.

: are direct evidences of past life.-:.help in the studies of extinct species and their 0 ~::....-structure and thus their

--~--tionary relation to the current species.=:'sometimes provide the link for evolutionary relaf ship between different species- are currently living.~.::.sthey provide convincing proof of organic evoluf

-. IVESOME EXAMPLES OF FOSSILS ..Ammonite - an inverteb~ate fossil related to moll" - like octopus. It is used to find

~sp~~'ifi~'gc~gi-61time period of the rock layer in ~. ch they are found. They' .ecame extinct along with dinosaurs.

- :":obite.Lan invertebrate fossil related to arthropods e crabs. It is used to find thex:s~f:5.tgeological time period of the rock layer in v;'-:= they are found .

.::.gQ.ti~- It is the fossil found in abundance in W 0 g, USA It is state fossil of-.'oming. It shows that ancient fish also did school: ~:::ke the modern fish.

~-:.WHY ARE HUMAN BEINGS WHO LOOK SO =TIERENT FROM EACHJJffiR IN TERlv'lS OF SIZE,COLOUR AND LOC~-- SAID TO BELONG TO THE

':::.~ffi SPECIES?.: _-Species can be defined as a group ofpopulations - se individuals have the potential-- interbreed and produce fertile offspring in nature, - -~ is possible between humanceings of different populations all around the earth : -~ look very different from eachorher in terms of size, colourand looks. That is wl.;: -'-=-~.J are all said to belong tothe- le speclC~s.

is. It--rEVOLUTIONARY TERMS, C.t\..l\[ WE SA-:"'--mCH AMONG BACTERIA,~PIDERS, FISH AND CHIMPANZEES FAVE ..::o~R BODY DESIGN? WHYOR WHY NOT?A We cannot say this particular group of organisrrs ~ a better body design.Evolution broadly means 1. generation of diversi _'::'::': 2. shaping of the diversity byenvironmental selection.Usually the older forms are simpler and the recent :_;::::}S have progressed into complexforms. As such there is no real progress in the id -:evolution as even the older andsimple forms still survive and flourish. In fact bac; ':::which look simpler than spiders orfish or chimpanzees survive in most inhospitabl ::... itatslike hot springs and ice inAntarctica which other organisms cannot do.

16. A MENDELIAN EXPERIMENT CONSIST3 JF BREEDING TALL PEAPLANTS BEARING VIOLET FLOWERS w:rE _.::iORTPEA PLANT BEARINGWHITE FLOWERS. THE PROGENY ALL BO?.::: 10LET FLOWERS, BUT

_ MOST HALF OF THEM WERE SHORT. THIS 3UG ESTS THAT THE GENETIC_l!\.KE UP OF THE TALL PARENT CAN BE DEPICTS) AS_ TLWW. (Work out this in your notebooks)

:~ A STUDY FOUND THAT CHILDREN WITH LIG=Q'-COLOURED EYES ARE .LIKELY TO HAVE PARENTS WITH LIGHT-COLOL~D EYES. ON TE-IISBASIS,

.~N WE SAY ANYTHING ABOUT WHETHER THE ='IGHT EYE COLOUR TRAIT- DOMINANT OR RECESSIVE? WHY OR WHY r -o-:=-?

.. No. This information is not sufficient as it does not ~ =-:. us what are the other traitsregarding the colour of the eyes and what is the percentage of occurrence of those traits ..As all the children are likely to have light coloured eyes .ike their parents this just means- at the parents must be homozygous fOT this trait.--·9. HOW ARE THE AREAS OF STUDY- EVOLUTIO. - AND CLASSIFICATIONDllERLINKED?. ' 'While classifying organisms, those with similar cha acteristics are placed in onegroup. This grouping of organisms usually results in ' ......:.~[archy.From this hierarchy wecan easily understand that the more characteristics t '(\ =: ecies will have in common themore closely they are related. The more closely they related the more recently they

-ould have had a common ancestor. Thus evolutions . relationships can be traced in, ,

classification of organisms.

_0. EXPLAIN THE TERMS HOMOLOGOUS AND -: -ALOGOUS ORGANS WITHEX!\,,1VIPLES?A. Homologous organs: Organs of different organis - similar in structure and differentin theirfunctions. Fe: Wing of bird, forelimbs of lizazc, frog-and human being, potato:Uld ginger ..Analogous organs: Organs of different organisms si : ar in function and different in their_tructurcs. Eg: Wings of butterfly and wings of bird.p tato and sweet potato (both storefood but potato is a stem whereas sweet potato is a r -T

21. WHAT EVIDENCE DO WE HA.VE FOR THE 3lGrN OF LIFE FROMINANIMATE MATTER?A. Tracing common ancestors back in time through extinct and extant species, leads us to::b~idea that multicellular animals arise from the jo' .. g of unicellular organisms. The.ceils that make up these organisms arc in turn made :-organic molecules that haveassembled into various organelles. This shows tha som~ point of time non-livingorganic molecules must have given rise to life. '

22. EXPLAIN HOW SEXUAL REPRODUCTIO~- _NES RISE TO MORE VIABLE,VARIATIONS THAN ASEXUAL REPRODUCE· _-. HOW DOES THIS AFFECTTHE EVOLUTION OF THOSE ORGANISMS 'IF:...T REPRODUCE SEXUALLY?A, In sexual reproduction there is accumulation of -iable variations generation aftergeneration, as two individuals with their own set of variations are involved in the process.Moreover during the formation of gametes there i segregation of chromosome pairsduring which genetic recombination results in more .ariations.

~~----=="-------'-,,~

- asexual reproduction only a single organism is involved. The variations arise due tominor inaccuracies during DNA copying in the organism just before cell division inreproduction. These variations are predictably small and few in number.. " a result greater diversity and hence more chances for evolution is possible in sexuallyreproducing organisms than asexually reproducing organisms.

2.J. HOWlS THE EQUAL GENETIC CONTRlBUTIOK OF MALE AND FEMALE.-\RENTS ENSURED IN TIIE PROGE};ry?

. Each cell in any organism has tWQ sets of chromosomes which occur in pairs. One setrues from father and the other comes from mother. Tl.is means each cell consists of two

copies of the same chromosome, one from father and one from mother for the same set of-' aracteristics.During the formation of germ cells or gametes, every germ cell gets one chromosomefrom each pair. That means half the number of chromosomes.-·i1cn two such germ cells, one from father and one fro mother combine, the paired. ndition of chromosomes 1S restored by half the chromosomes coming from father andaalf the chromosomes coming from mother.This means that there is equal genetic contribution from male and female parents to theprogeny.

2. ONLY VARIATIONS THAT CONFER AN AD Al'ITAGE TO AN INDIVIDUALORGANISM WILL SURVNE]}-T A POPULATION. DO YOU AGREE WITH THIS-TATEMENT? WHY OR WHY NOT?_ . Variations occurring in an individual organism will urvive only when they are passed -""'n,by the process of reproduction followed by natural selection of these traits. In tl:i.e 'absence of these processes the variations will not survive in a population.

::.xtra..Iiller and Urey ExperimentOparin from Russia and Haldane from UK, suggested that life must have been developedfrom simple inorganic molecules or inanimate matte present on the earth soon after it

'as formed. 'That inanimate matter on early earth consisted of ammonia, methane and hydrogensulphide over water under extremely hot conditions.z d there was continuous Iightening·00.

- filler and Urey assembled an atmosphere similar to's by introducing methane,ammonia and hydrogen sulphide over boiling water; a round shaped flask. TIletemperature was maintained just belov/lOOoC and sparks were passed through themixture of gases to simulate lightning. Within a we- 15% of carbon from methane has

een converted into simple carbon compounds like amino acids which make up proteinmolecules, This shows that life originated from inanimate matter.

~~ TIffi THREE TYPES OF BLOOD VESSELS IN OUR BODY?. ...:..blood vessels that carry blood from heart to various organs of the body- blood vessels that carry blood from various organs to the heart

.es -.::..The smaller vessels into which the arteries and veins end near the organs._- 1 ~ are made up of a single layer of cells. Exchange of material between the

d the surrounding cells takes place across this thin wall.

IS THE FUNCTION OF PLATELETS?.~ of leakage of blood from injuredblood vessels leads to a loss of blood or a loss

1IfCl1Si.·'IT.1e which would reduce the efficiency of the pumping organ ie heart. Plateletseese injuries by clotting the blood at the points ofinjury .

.. IS LYMPH AND WHAT IS ITS FUNCTION?amount of plasma, proteins and white blood cells of the blood escape from thecapillaries into the spaces between the cells (intercellular spaces) in tissues to form'uid or lymph. This lymph flows into the lymphatic capillaries from the

ular spaces. The lymphatic capillaries join to form lymphatic vessels which openger veins near the heart. .

~ . ph is colourless, has WBC and similar composition as plasma except for few

ons:carries digested and absorbed fat from intestine to different parts of the body.

carries excess of fluid circulating it between blood and intercellular spaces.

~: A..% THE C01-.fPONENTS OF TIIS TRfu~SPORT SYSTEM IN IDGHL YANISEDfLANTS?

- to move water and minerals obtained from the soil to the upper parts of the plantI - to transport products ofphotosyntaesis, hormones and other organicnmds prepared in the leaf to other parts of the plant.

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ARE WATER AND ~'ERALS TRAl'lSPORTED IN PLANTS?~~ssuie: The root cells in contact V:;i~the soil actively take up -iQns.. is':Wbre concentration of these ions in the root cells than the soil,'

_ I. wi1JDlove'i~}c>~heroot foii.:Owi~g·tb:eions by oS~1osis.This steady movement of- into the root forms a column of water that is steadily pushed upward consequently.

_ pressure is ~p:oQ,ghto push water in the network of xylem vessels and tracheids inof small heig.ht~. .. r . - • . .' .

~=.=ir=ati.on: The loss of water in the form of vapour from the aerial parts of the plant ism-as tfan~piration.· .

ration ofwater from the cells of a leaf creates a suction which pulls water from thecells of stems. and further from the xylem cells of roots.

.a, pressure becomes more important to move water during night and transpiration ismajor force that moves water during day time when the stomata are open.

III